Prognostic significance of histological categorization of desmoplastic reaction in colorectal liver metastases

Desmoplastic reaction (DR) involves the growth of fibrous or connective tissues around a tumor and has recently attracted attention as an indicator of malignant potential. Previous studies have confirmed that histological categorization of DR in the primary tumor is an independent prognostic factor in patients with colorectal liver metastases (CRLM). However, it remains unclear whether the DR status of the metastatic liver lesion (DRliver) is a useful prognostic factor. This pathological review evaluated records from 204 patients who underwent hepatectomy for CRLM at the National Defense Medical College Hospital in Japan. Each case's DRliver was classified as mature, intermediate, or immature based on the presence of keloid-like collagen and myxoid stroma in the metastatic liver lesion. This resulted in 12 cases of mature DRliver, 101 cases of intermediate DRliver, and 91 cases of immature DRliver. There was a significant correlation between the DR statuses of the primary tumor and the metastatic liver lesion (Spearman's rho = 0.3, P = 0.0001). The 5-year relapse-free survival rates after hepatectomy were 33.8% for mature/intermediate DRliver and 16.7% for immature DRliver (P = 0.0021). The 5-year overall survival rate after hepatectomy was higher in the mature/intermediate DRliver group (64.8%) than in the immature DRliver group (35.0%; P = 0.0012). The multivariate analysis confirmed that DRliver categorization could independently predict relapse-free survival and overall survival. In conclusion, DRliver categorization may be valuable for predicting prognosis after hepatectomy among patients with CRLM.